The Polish Wikipedia uses FlaggedRevisions or PendingChanges and has deployed both notices upon opening a page and a different text on the "Save" button to reduce confusion by new editors. These notices are not appearing in VisualEditor.
Version: unspecified
Severity: major
That's not the real issue.
FlaggedRevs are enabled globally, for all pages, and *all non-autoreviewed edits require review before they are shown*; the only groups exempt from review are reviewers themselves and bots. (You can choose to view the so-called 'unstable' versions of pages instead of 'stable' ones in preferences.)
Information about this is shown to viewers before, during and after editing (using the messages pointed out in the issue report WhatamIdoing linked) – but VE shows it in none of these contexts.
I would consider this a blocker to deployment to anonymous users at least.
Yeah, this isn't good; we've actually just-about fixed it and will deploy it the morning (San Francisco time).